Description: Rogue backends can cause DoS of guests via high frequency events (blkfront)
References:
 https://xenbits.xen.org/xsa/advisory-391.html
 https://xenbits.xen.org/xsa/xsa391-linux-1.patch
Notes:
 carnil> Fixed as well in 5.15.11 for 5.15.y.
Bugs:
upstream: released (5.16-rc7) [0fd08a34e8e3b67ec9bd8287ac0facf8374b844a]
5.10-upstream-stable: released (5.10.88) [8ac3b6ee7c9ff2df7c99624bb1235e2e55623825]
4.19-upstream-stable: released (4.19.222) [269d7124bcfad2558d2329d0fe603ca20b20d3f4]
4.9-upstream-stable: released (4.9.294) [25898389795bd85d8e1520c0c75c3ad906c17da7]
sid: released (5.15.15-1)
5.10-bullseye-security: released (5.10.92-1)
4.19-buster-security: released (4.19.232-1)
4.9-stretch-security: released (4.9.303-1)